The present invention relates to control systems for vehicle air conditioners and more particularly to a control system for selectively inducting air into an air duct from inside and outside the passenger compartment of a vehicle.
With vehicle air conditioners, a variety of techniques are heretofore known in the art which automatically control the induction of air from inside the compartment and the induction of air from outside the compartment and these known techniques include, for example, systems of the type in which an air induction electromechanical actuator is operated by a switch which is mechanically operatively associated with the position of temperature adjusting means such as an air mixing damper, thereby automatically effecting changeover from the induction of the inside air to the induction of the outside air or vice versa.
However, this type of known system is linearly associated operatively only with temperature adjusting means so that due to the effects of variations in the thermal exchanging capacity of thermal exchangers disposed in an air duct, such as, the operation and stopping of a cooling compressor, variations in the compressor rotation speed due to the vehicle engine or variations in the temperature of the engine cooling water, the temperature of the supply air is sometimes varied even for the same position of the temperature adjusting means and thus it is impossible to effect change-over from one mode of air induction to another on the basis of a predetermined supply air temperature.